Patent application title: Omnidirectional antenna radiation element

Abstract:

An antenna element for use in an antenna assembly is provided. The antenna
element includes a cylindrical tube. The antenna element also includes a
plurality of fingers, each finger having a first end that is connected to
the cylindrical tube and a second end that is free. Each finger protrudes
inward from a wall of the cylindrical tube. The free end of each finger
has an aperture configured to allow the finger to be soldered to a pipe
disposed through a generally circular opening. An antenna assembly having
at least one antenna element is also provided.

Claims:

1. For use in an antenna assembly, an antenna element comprising:a
cylindrical tube; anda plurality of fingers, each finger having a first
end that is connected to the cylindrical tube and a second end that is
free,wherein each finger protrudes inward from a wall of the cylindrical
tube.

2. The antenna element as set forth in claim 1, wherein the free end of
each finger is curved, and the curved free ends of every finger together
form a generally circular opening.

3. The antenna element as set forth in claim 2, wherein the free end of
each finger has an aperture configured to allow the finger to be soldered
to a pipe disposed through the generally circular opening.

4. The antenna element as set forth in claim 1, wherein the fingers are
radially symmetrical about an axis through a center of the antenna
element.

5. The antenna element as set forth in claim 1, wherein the fingers are
disposed at one end of the antenna element.

6. The antenna element as set forth in claim 1, wherein the fingers are
disposed near one end of the antenna element.

7. The antenna element as set forth in claim 1, wherein each finger is
formed from a portion of the wall of the cylindrical tube.

8. The antenna element as set forth in claim 2, wherein each finger has
sufficient flexibility to easily yield to a pipe passing through the
generally circular opening.

9. An antenna assembly having at least one antenna element, the at least
one antenna element comprising:a cylindrical tube; anda plurality of
fingers, each finger having a first end that is connected to the
cylindrical tube and a second end that is free,wherein each finger
protrudes inward from a wall of the cylindrical tube.

10. The antenna assembly as set forth in claim 9, wherein the free end of
each finger is curved, and the curved free ends of every finger together
form a generally circular opening.

11. The antenna assembly as set forth in claim 10, wherein the free end of
each finger has an aperture configured to allow the finger to be soldered
to a pipe disposed through the generally circular opening.

12. The antenna assembly as set forth in claim 9, wherein the fingers are
radially symmetrical about an axis through a center of the antenna
element.

13. The antenna assembly as set forth in claim 9, wherein the fingers are
disposed at one end of the antenna element.

14. The antenna assembly as set forth in claim 9, wherein the fingers are
disposed near one end of the antenna element.

15. The antenna assembly as set forth in claim 9, wherein each finger is
formed from a portion of the wall of the cylindrical tube.

16. The antenna assembly as set forth in claim 10, wherein each finger has
sufficient flexibility to easily yield to a pipe passing through the
generally circular opening.

17. A method for manufacturing an antenna element, the method
comprising:providing a cylindrical tube; andforming a plurality of
fingers, each finger having a first end that is connected to the
cylindrical tube and a second end that is free,wherein each finger
protrudes inward from a wall of the cylindrical tube.

18. The method as set forth in claim 17, wherein the free end of each
finger is curved, and the curved free ends of every finger together form
a generally circular opening.

19. The method as set forth in claim 18, wherein the free end of each
finger has an aperture configured to allow the finger to be soldered to a
pipe disposed through the generally circular opening.

20. The method as set forth in claim 17, wherein the fingers are radially
symmetrical about an axis through a center of the antenna element.

Description:

CROSS-REFERENCE TO RELATED APPLICATION(S) AND CLAIM OF PRIORITY

[0001]The present application is related to U.S. Provisional Patent No.
61/268,089, filed Jun. 9, 2009, entitled "OMNIDIRECTIONAL ANTENNA
RADIATION ELEMENT". Provisional Patent No. 61/268,089 is assigned to the
assignee of the present application and is hereby incorporated by
reference into the present application as if fully set forth herein. The
present application hereby claims priority under 35 U.S.C. §119(e)
to U.S. Provisional Patent No. 61/268,089.

TECHNICAL FIELD OF THE INVENTION

[0002]The present application relates generally to dipole antennas and,
more specifically, to an improved omnidirectional antenna radiation
element for use in a dipole antenna.

BACKGROUND OF THE INVENTION

[0003]A basic dipole antenna is an antenna that can be made by a simple
arrangement of wires, for the purpose of transmitting or receiving radio
frequency energy. Dipole antennas, in their most basic form, are among
the simplest antennas. However, dipole antennas have a multitude of
practical uses, including deployment in cellular radio systems (e.g.,
subscriber units and base stations).

[0004]Performance of dipole antennas can be enhanced by combining two or
more antenna elements. One type of antenna element is disclosed in U.S.
Pat. No. 5,105,199 (the '199 patent) to Ukmar, titled "Method and
Apparatus for Tube Element Bracket," which is incorporated herein by
reference. A prior art antenna element, such as the antenna element
described in the '199 patent, has four small openings in the cross
sections of the element, making it difficult to pass feed lines or
phasing harnesses from element to element during antenna assembly.
Additionally, a prior art antenna element according to the '199 patent
has only two soldering points to secure the element to the central metal
rod, thus making the soldered connection less secure. These shortcomings
may be unacceptable to an antenna manufacturer who builds his reputation
of failure-proof products.

[0005]Accordingly, there is a need in the art for an improved
omnidirectional antenna radiation element.

SUMMARY OF THE INVENTION

[0006]An antenna element for use in an antenna assembly is provided. The
antenna element includes a cylindrical tube. The antenna element also
includes a plurality of fingers, each finger having a first end that is
connected to the cylindrical tube and a second end that is free. Each
finger protrudes inward from a wall of the cylindrical tube. An antenna
assembly having at least one antenna element is also provided.

[0007]A method for manufacturing an antenna element is provided. The
method includes providing a cylindrical tube. The method also includes
forming a plurality of fingers, each finger having a first end that is
connected to the cylindrical tube and a second end that is free. Each
finger protrudes inward from a wall of the cylindrical tube.

[0008]Before undertaking the DETAILED DESCRIPTION OF THE INVENTION below,
it may be advantageous to set forth definitions of certain words and
phrases used throughout this patent document: the terms "include" and
"comprise," as well as derivatives thereof, mean inclusion without
limitation; the term "or," is inclusive, meaning and/or; the phrases
"associated with" and "associated therewith," as well as derivatives
thereof, may mean to include, be included within, interconnect with,
contain, be contained within, connect to or with, couple to or with, be
communicable with, cooperate with, interleave, juxtapose, be proximate
to, be bound to or with, have, have a property of, or the like; and the
term "controller" means any device, system or part thereof that controls
at least one operation, such a device may be implemented in hardware,
firmware or software, or some combination of at least two of the same. It
should be noted that the functionality associated with any particular
controller may be centralized or distributed, whether locally or
remotely. Definitions for certain words and phrases are provided
throughout this patent document, those of ordinary skill in the art
should understand that in many, if not most instances, such definitions
apply to prior, as well as future uses of such defined words and phrases.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009]For a more complete understanding of the present disclosure and its
advantages, reference is now made to the following description taken in
conjunction with the accompanying drawings, in which like reference
numerals represent like parts:

[0010]FIGS. 1A and 1B depict orthogonal and cross-sectional views of a
conventional antenna radiation element, such as described in U.S. Pat.
No. 5,105,199;

[0011]FIGS. 2A, 2B, and 2C illustrate orthogonal, cross-sectional, and
longitudinal views, respectively, of an omnidirectional antenna radiation
element according to one embodiment of the present disclosure; and

[0012]FIG. 3 illustrates an antenna assembly utilizing multiple
omnidirectional antenna radiation elements according to one embodiment of
the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

[0013]FIGS. 1A through 3, discussed below, and the various embodiments
used to describe the principles of the present disclosure in this patent
document are by way of illustration only and should not be construed in
any way to limit the scope of the disclosure. Those skilled in the art
will understand that the principles of the present disclosure may be
implemented in any suitably arranged wireless network.

[0014]FIGS. 1A and 1B depict orthogonal and cross-sectional views of one
example of a conventional antenna radiation element. The illustrations in
FIGS. 1A and 1B are reproduced from FIGS. 3 and 5 of the '199 patent.
Antenna element 100 includes a hollow, metal (often brass), cylindrical
tube 102 with walls that are relatively thin in relation to the diameter
of cylindrical tube 102. Conventional dimensions of cylindrical tube 102
are one and one-half inch outer diameter (1-1/2'' O.D.) and a wall
thickness of 0.032 inch. It is understood that these dimensions may
differ from one design to another.

[0015]Near one end of cylindrical tube 102 are two brackets 104 disposed
on opposite sides of cylindrical tube 102. The brackets 104 are formed by
cutting slits along opposite sides of the circumference of cylindrical
tube 102, then using a die to deform the resulting arcuate sections
inward. The shape of brackets 104 can be seen in cross-sectional view in
FIG. 1B. The configuration of brackets 104 as seen in FIG. 1B is
sometimes referred to a "figure eight" or "hourglass" configuration,
because of the shape formed by brackets 104.

[0016]The middle section of each bracket 104 is curved outward to fit
closely against a metal pipe 106 that is inserted through the middle of
antenna element 100. Each bracket 104 may include a small hole in the
middle section to provide a point for soldering bracket 104 to metal pipe
106. The positions of brackets 104 and the walls of cylindrical tube 102
create four openings in the cross-section of antenna element 100. These
openings are indicated by the reference letters A, B, C, and D.

[0017]During assembly of an antenna, one or more feed lines or phasing
harnesses (not shown) may be passed through one or several of the
openings A-D of antenna element 100. The feed lines serve to phase
together multiple antenna elements, such as antenna element 100. These
feed lines run on the outside of the metal pipe 106 and are soldered to
the outside of pipe 106, but inside cylindrical tube 102. Typically, each
feed line is a copper-clad cable approximately 0.144-0.25 inches in
diameter. Due to the shape and small size of each opening A-D, it is not
uncommon for all of the feed lines to have some difficulty passing
through the selected opening. Likewise, because of the relative rigidity
and close dimensions of brackets 104 in the hourglass configuration, it
is not uncommon during antenna assembly for the multiple feed lines to
have some difficulty passing between the two brackets 104. These
shortcomings of the hourglass configuration of antenna element 100 are
resolved by advantageous embodiments of the present disclosure.

[0018]FIGS. 2A, 2B, and 2C illustrate orthogonal, cross-sectional, and
longitudinal views, respectively, of an omnidirectional antenna radiation
element according to one embodiment of the present disclosure. The
uniqueness of antenna element 200 resides in the manner in which one end
of antenna element 200 is formed and then attaches, by means of a
soldering process, to a conductive center support, so as to provide
mechanical stability and integrity of the antenna assembly. The
embodiment of antenna element 200 shown in FIG. 2 is for illustration
only. Other embodiments of antenna element 200 may be used without
departing from the scope of this disclosure.

[0019]In the illustrated embodiment, antenna element 200 includes a
hollow, metal cylindrical tube 202 with walls that are relatively thin in
relation to the diameter of cylindrical tube 202. In certain embodiments,
cylindrical tube 102 has an outer diameter of one and one-half to two
inches (1-1/2''-2'' O.D.) and a wall thickness of approximately 0.03
inch. In certain embodiments, cylindrical tube 202 is made from copper or
brass. It is noted that these dimensions and materials are for example
purposes only. Other dimensions and materials for cylindrical tube 202
are possible.

[0020]At one end of cylindrical tube 202 are three fingers 204 disposed
around a circumference of cylindrical tube 202. Each finger has one
"free" end and one end that is connected to cylindrical tube 202. By
"free", it is meant that the end is unconnected or unattached to any
other body or member at the time antenna element 200 is manufactured.
During antenna assembly, the free end of each finger may be attached to a
center pipe, as described below.

[0021]The fingers 204 are formed by cutting slits in cylindrical tube 202,
both parallel and perpendicular to the axis of cylindrical tube 202. Then
a die or other manufacturing tool is used to deform the resulting arcuate
sections, so that they bend or protrude inward, as shown in FIGS. 2A and
2B. In advantageous embodiments, fingers 204 have approximately the same
length and width, and are disposed one hundred twenty degrees
(120°) of arc apart. Thus, fingers 204 are radially symmetrical
about the axis of cylindrical tube 202. In certain embodiments, fingers
204 may be disposed near the end of cylindrical tube 202, or somewhere
else along the length of cylindrical tube 202, rather than at the end of
cylindrical tube 202.

[0022]Each finger 204 bends inward towards the center axis of antenna
element 200. The free end of each finger 204 is curved. Together, the
curved free ends form a generally circular opening. During antenna
assembly, a metal center pipe 208 (shown in FIG. 2B) is inserted through
the middle of antenna element 200 and through the circular opening. The
radius of the curve of the free end of each finger 204 is chosen to allow
the free end of each finger 204 to fit closely against the center pipe
208. Because the free end of each finger 204 is unattached, each finger
204 exhibits a certain amount of flexibility for movement in a plane
perpendicular to the center axis of antenna element 200. This flexibility
allows each finger 204 to easily yield its position slightly as center
pipe 208 is inserted through the middle of antenna element 200, thus
allowing easy insertion through antenna element 200. The flexibility of
each finger 204 provides a desirable amount of dimensional tolerance
during manufacture of antenna element 200, and provides desirable
adjustability during antenna assembly. For example, if any finger 204 is
slightly short or long, or if any finger 204 is bent too far inward, or
not bent far enough inward, it may be adjusted by flexing the free end
inward or outward as needed.

[0023]The flexibility of fingers 204 offers a significant improvement over
the brackets 104 found in the hourglass configuration of antenna element
100 shown in FIG. 1. Each end of bracket 104 is connected to the wall of
cylindrical tube 102. The lack of a free end in bracket 104 results in a
much more rigid shape. The rigidity of brackets 104 results in lower
dimensional tolerance during manufacture and less adjustability during
antenna assembly. For example, if brackets 104 are too close together,
the resulting space between them will be too small, making it difficult
or impossible to insert metal pipe 106 through the space. On the other
hand, if brackets 104 are too far apart, the metal pipe 106 may slip
right through antenna element 100 without any friction to hold metal pipe
106 in place. This would make reliable soldering of antenna element 100
to metal pipe 106 difficult or impossible.

[0024]In the middle of the curved free end of each finger 204 is a small
soldering hole 206. Soldering hole 206 is an aperture that passes
completely through the thickness of finger 204. Soldering hole 206
provides a point for soldering each finger 204 to center pipe 208.
Because each finger 204 has a soldering hole 206, there are a total of
three soldering points for soldering antenna element 200 to center pipe
208. The use of three soldering points spaced evenly around the
circumference of center pipe 208 allows for a very strong bond between
antenna element 200 and center pipe 208. This is an improvement over the
hourglass configuration of antenna element 100. Antenna element 100
includes only two soldering points, one in the middle of each bracket
104. The use of only two soldering points results in a weaker bond
between antenna element 100 and metal pipe 106.

[0025]The use of three evenly-spaced soldering points in antenna element
200 offers another advantage over the hourglass configuration of antenna
element 100. Like a three-legged stool, the three bonding points of
antenna element 200 around center pipe 208 create a rigid, stable
assembly with no degree of freedom. In other words, antenna element 200
may not wiggle, twist, or shift back and forth with respect to center
pipe 208. On the other hand, antenna element 100 includes only two
soldering points, located on opposite sides of metal pipe 106. Thus,
antenna element 100 may be stable across one axis, but may be
significantly prone to wiggle, toggle, or shift across another axis. Like
a two-legged stool, antenna element 100 is not completely stable.

[0026]The positions of fingers 204 and the walls of cylindrical tube 202
create three openings 210 in the cross-section of antenna element 200.
During assembly of an antenna, multiple feed lines and/or phasing
harnesses (not shown) may be passed through the openings 210 of antenna
element 200. In certain embodiments, each phasing harness is a cable
approximately 0.142-0.25 inches in diameter.

[0027]Due to their number and shape, openings 210 present a significant
improvement over the openings A-D of antenna element 100 shown in FIG. 1.
Because there are only three openings instead of four, each opening 210
is larger than any of the openings A-D of antenna element 100.
Additionally, the shape of each opening 210 has fewer concave curves and
narrow dimensions than the openings A-D of antenna element 100. Thus, the
phasing harnesses are less likely to get caught up in, or pinched by,
openings 210. Also, because fingers 204 are radially symmetrical, each
opening 210 has the same size and shape. Thus, multiple antenna elements
200 can be interconnected in a corporate feed arrangement by means of the
phasing harnesses (with the phasing harnesses placed through one or all
of openings 210) without regard to the rotational orientation of each
antenna element 200. This approach provides a precise, phase-matched
feeding of antenna elements 200 with the phasing harnesses accommodated
inside cylindrical tube 202 but outside center pipe 208.

[0028]The radiation element of the present disclosure is typically used in
multiple pairs as radiating elements of land mobile radio low- or
high-gain antennas. The length of each element, such as antenna element
200, corresponds to approximately 0.5 times the wavelength of the
electromagnetic wave the antenna is designed to transmit and/or receive.
The number of antenna elements 200 that may be phased together determines
the number of phasing harness cables that are passed through each element
200. The larger size and advantageous shape of the openings 210 in each
element 200 may allow for a more complex phasing harness to be used in
the antenna assembly. This, in turn, allows for more antenna elements 200
to be connected together, thus creating a higher gain antenna.

[0029]FIG. 3 illustrates an antenna assembly utilizing multiple
omnidirectional antenna radiation elements according to one embodiment of
the present disclosure. The embodiment of the antenna assembly 300 shown
in FIG. 3 is for illustration only. Other embodiments of the antenna
assembly 300 may be used without departing from the scope of this
disclosure.

[0030]Antenna assembly 300 includes two antenna elements 302, an antenna
element 304 containing a signal splitter, two more antenna elements 306,
a antenna element 308 known in the art as a "choke can", a metal pipe
310, a semi-rigid cable 312, and a connector 314. In certain embodiments,
each of the antenna elements 302-308 may be equivalent or similar to the
omnidirectional antenna radiation element 200 shown in FIG. 2. Similarly,
metal pipe 310 may be equivalent or similar to center pipe 208.

[0031]Each of the antenna elements 302-308 is soldered to metal pipe 310.
In certain embodiments, metal pipe 310 is composed of brass. In
advantageous embodiments, metal pipe 310 includes a hollow core. The
semi-rigid cable 312 runs from connector 314, through metal pipe 310, to
the signal splitter in antenna element 304. In other embodiments, metal
pipe 310 may be a rod having a solid core.

[0032]Although the present disclosure has been described with exemplary
embodiments, various changes and modifications may be suggested to one
skilled in the art. It is intended that the present disclosure encompass
such changes and modifications as fall within the scope of the appended
claims.